JP7334892B1 - Rotation angle detection device, power transmission device, rotation angle detection method, and robot - Google Patents

Abstract

The present invention provides a technology capable of detecting multiple rotation angles of a high-speed side member of a power transmission device. A power transmission device (1) includes a first member (10) and a second member (20). The first member 10 rotates at a first rotational speed. The second member 20 rotates at a second rotational speed lower than the first rotational speed as the first member 10 rotates. The rotation angle detection device includes a first detection section, a second detection section, and a calculation section. The first detection unit detects the rotation angle of the first member 10. The second detection unit detects the rotation angle of the second member 20. The calculation unit outputs the multiple rotation angle of the first member 10 based on the rotation angle detected by the first detection unit and the rotation angle detected by the second detection unit. [Selection diagram] Figure 2

Description

The present invention relates to a rotation angle detection device, a power transmission device, a rotation angle detection method, and a robot.

2. Description of the Related Art Conventionally, a speed reducer is known that reduces rotational motion output from a motor. A speed reducer is, for example, incorporated in a joint of an industrial robot and used to transmit the power of a motor to an arm. A conventional speed reducer is described in Patent Document 1, for example.
JP-A-2005-312223

A robot equipped with this type of speed reducer needs to know the rotation angle of the arm when the power is turned on. A conventional robot grasps the rotation angle of its arm based on the output signal of the encoder mounted on the motor. However, this method requires a motor encoder. Therefore, it is required to detect the rotation angle of the arm in the speed reducer without depending on the encoder of the motor.

In order to detect the rotation angle of the arm in the speed reducer, for example, it is conceivable to attach a sensor for detecting the rotation angle to a member on the output side of the speed reducer. However, in that case, a high-resolution sensor is required, which increases the manufacturing cost of the speed reducer. On the other hand, if the rotation angle of a member that rotates at high speed is detected on the input side of the speed reducer, the rotation angle can be easily detected with high resolution. However, when detecting the rotation angle on the input side of the decelerator, it is necessary to detect the absolute angle in multiple rotations, not the absolute angle in one rotation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique capable of detecting multiple rotation angles of a member on the high speed side of a power transmission device.

A first invention is a power transmission device having a first member that rotates at a first rotational speed, and a second member that rotates at a second rotational speed lower than the first rotational speed as the first member rotates. A rotation angle detection device comprising: a first detection unit for detecting the rotation angle of the first member; a second detection unit for detecting the rotation angle of the second member; and detected by the first detection unit a calculation unit that outputs a multi-rotation angle of the first member based on the rotation angle and the rotation angle detected by the second detection unit, wherein the second detection unit outputs the multi-rotation angle with a predetermined number of bits; and outputting the discrete value shown, the output value of the first detection unit is A, the output value of the second detection unit is P, the number of bits is B, and the gear ratio of the power transmission device is N, and the calculation is performed The section calculates the multi-rotation angle of the first member based on A, P, B , and N.

A second aspect of the invention is a power transmission device having a first member that rotates at a first rotation speed, and a second member that rotates at a second rotation speed lower than the first rotation speed as the first member rotates. 3, a rotation angle detection method for detecting multiple rotation angles of the first member, comprising: a first step of detecting a rotation angle of the first member and a rotation angle of the second member; and detection by the first step. a second step of outputting a multi-rotation angle of the first member based on the rotation angle of the first member and the rotation angle of the second member, wherein the second step includes: a predetermined bit A is the output value of the rotation angle of the first member, P is the output value of the rotation angle of the second member, B is the number of bits, and the gear ratio of the power transmission device is output. N, and in the second step, based on A, P, B, and N, the multiple rotation angle of the first member is output .

A third aspect of the invention is a power transmission device, comprising: a first member rotating at a first rotation speed; and a second member rotating at a second rotation speed lower than the first rotation speed as the first member rotates. a member, a first detector that detects the rotation angle of the first member, a second detector that detects the rotation angle of the second member, and an annular body, wherein the second detector detects a predetermined Output a discrete value indicated by the number of bits of A, the output value of the first detection unit is A, the output value of the second detection unit is P, the number of bits is B , the gear ratio of the power transmission device is N, , the calculation unit calculates the multi-rotation angle of the first member based on A, P, B, and N.

According to the first, second, and third inventions, the multiple rotation angles of the first member can be output.

FIG. 1 is a schematic diagram of a robot. FIG. 2 is a longitudinal sectional view of the power transmission device. FIG. 3 is a view of the power transmission device viewed from one side in the axial direction. FIG. 4 is a diagram of the power transmission device viewed from the other side in the axial direction. FIG. 5 is a cross-sectional view of the power transmission device viewed from the AA position in FIG. FIG. 6 is a partial vertical cross-sectional view of the annular body in the vicinity of the sensor substrate. FIG. 7 is a plan view of the sensor substrate. FIG. 8 is a partial plan view of the sensor substrate. FIG. 9 is a circuit diagram of the first bridge circuit. FIG. 10 is a circuit diagram of the second bridge circuit. FIG. 11 is a circuit diagram of the third bridge circuit. FIG. 12 is a circuit diagram of the fourth bridge circuit. FIG. 13 is a graph showing temporal changes in the measured value of the third voltmeter and the measured value of the fourth voltmeter. FIG. 14 is a graph showing an example of output values of the first detection section and the second detection section. FIG. 15 is a view of the power transmission device according to the first modification as viewed from one side in the axial direction. FIG. 16 is a view showing a portion of the second member and annular body;

Exemplary embodiments of the present application are described below with reference to the drawings.

<1. About the robot>
FIG. 1 is a schematic diagram of a robot 100 equipped with a power transmission device 1 according to one embodiment. The robot 100 is, for example, a so-called industrial robot that carries out operations such as transportation, processing, and assembly of parts in a manufacturing line for industrial products. As shown in FIG. 1, the robot 100 includes a base frame 101, an arm 102, a motor 103, and a power transmission device 1.

Arm 102 is rotatably supported on base frame 101 . Motor 103 and power transmission device 1 are incorporated in joints between base frame 101 and arm 102 . When the drive current is supplied to the motor 103, the motor 103 outputs rotational motion. Also, the rotational motion output from the motor 103 is reduced by the power transmission device 1 and transmitted to the arm 102 . As a result, the arm 102 rotates with respect to the base frame 101 at the decelerated speed.

<2. Configuration of Power Transmission Device>
Next, the detailed structure of the power transmission device 1 will be described.

In the following description, the direction parallel to the central axis 9 of the power transmission device 1 will be referred to as the "axial direction", the direction perpendicular to the central axis 9 of the power transmission device 1 will be referred to as the "radial direction", and the central axis 9 of the power transmission device 1 will be referred to as A direction along the center arc is called a “circumferential direction”. However, the above-mentioned "parallel direction" also includes substantially parallel directions. Moreover, the above-mentioned "perpendicular direction" also includes a substantially perpendicular direction.

FIG. 2 is a longitudinal sectional view of the power transmission device 1 according to one embodiment. FIG. 3 is a view of the power transmission device 1 viewed from one axial side (left side in FIG. 2). FIG. 4 is a view of the power transmission device 1 viewed from the other side in the axial direction (the right side in FIG. 2). FIG. 5 is a cross-sectional view of the power transmission device 1 viewed from the AA position in FIG. In order to avoid complication of the drawing, hatching indicating a cross section is omitted in FIG.

This power transmission device 1 is a wave motion reduction gear. The power transmission device 1 reduces the rotational motion at the first rotational speed obtained from the motor 103 to a second rotational speed lower than the first rotational speed. As shown in FIGS. 2 to 5, the power transmission device 1 has a first member 10, a second member 20, an annular body 30, and a wave generator 40. As shown in FIGS.

The first member 10 is a member that rotates at a first rotational speed before deceleration. The first member 10 is connected to the output shaft of the motor 103 . The first member 10 extends axially along the central axis 9 . The first member 10 of this embodiment has a cylindrical shape centered on the central axis 9 . The first member 10 axially penetrates the power transmission device 1 . Note that the first member 10 may be the same member as the output shaft of the motor 103 .

The second member 20 is a member that rotates at a second rotation speed lower than the first rotation speed as the first member 10 rotates. The second member 20 is fixed with respect to the arm 102 . The second member 20 is arranged radially outward of the external teeth 32 to be described later. The rigidity of the second member 20 is sufficiently higher than the rigidity of the later-described body portion 31 of the annular body 30 .

The second member 20 is an annular internal gear centered on the central axis 9 . The second member 20 has a plurality of internal teeth 21 . The plurality of internal teeth 21 protrude radially inward from the radial inner surface of the second member 20 . The plurality of internal teeth 21 are arranged at a constant pitch in the circumferential direction on the inner peripheral surface of the second member 20 .

The annular body 30 is a flexurally deformable annular external gear. The annular body 30 is fixed with respect to the base frame 101 . As shown in FIGS. 2 and 5, the annular body 30 has a body portion 31, a plurality of external teeth 32, a base portion 33, and a thick portion .

The trunk portion 31 is a cylindrical portion centered on the central axis 9 . One axial end of the body portion 31 is connected to the base portion 33 . The trunk portion 31 extends from the radially inner end portion of the base portion 33 toward the other side in the axial direction. The other axial end of the body portion 31 is located radially outside the wave generator 40 and radially inside the second member 20 . Since the trunk portion 31 has flexibility, it can be flexurally deformed in the radial direction.

The plurality of external teeth 32 protrude radially outward from the radial outer surface of the body portion 31 . The plurality of external teeth 32 are arranged on the radially outer surface of the other axial end of the body portion 31 . The plurality of external teeth 32 are arranged at a constant pitch in the circumferential direction. A portion of the plurality of external teeth 32 and a portion of the plurality of internal teeth 21 are meshed with each other. The number of internal teeth 21 that the second member 20 has and the number of external teeth 32 that the annular body 30 has are slightly different.

The base portion 33 surrounds the central axis 9 and extends in a direction intersecting the central axis 9 . Base portion 33 preferably extends along a plane orthogonal to central axis 9 . The base portion 33 extends radially outward from one axial end of the body portion 31 . Also, the base portion 33 has an annular shape surrounding the central axis 9 . Since the base portion 33 is thin, it can be slightly bent and deformed.

The thick portion 34 is an annular portion positioned radially outward of the base portion 33 . The thickness of the thick portion 34 in the axial direction is greater than the thickness of the base portion 33 in the axial direction. The thick portion 34 is fixed to the base frame 101 directly or via another member.

The wave generator 40 is a mechanism that causes the annular body 30 to undergo periodic bending deformation. The wave generator 40 is arranged radially inside the external teeth 32 . Wave generator 40 has cam 41 and flexible bearing 42 . In this embodiment, the first member 10 and the cam 41 are formed from a single piece. However, the cam 41 may be a component separate from the first member 10 . In that case, the cam 41 should be fixed to the first member 10 . A radial outer surface of the cam 41 is elliptical around the central axis 9 .

The flexible bearing 42 is a flexurally deformable bearing. The flexible bearing 42 is arranged between the radially outer surface of the cam 41 and the radially inner surface of the trunk portion 31 of the annular body 30 .

The inner ring of the flexible bearing 42 contacts the radial outer surface of the cam 41 . The outer ring of the flexible bearing 42 contacts the radial inner surface of the trunk portion 31 . Therefore, the trunk portion 31 deforms into an elliptical shape along the radial outer surface of the cam 41 . As a result, the external teeth 32 of the annular body 30 and the internal teeth 21 of the second member 20 are meshed at two locations corresponding to both ends of the long axis of the ellipse. At other positions in the circumferential direction, the external teeth 32 and the internal teeth 21 do not mesh.

When the motor 103 is driven, the first member 10 and the cam 41 rotate about the central axis 9 at the first rotation speed. As a result, the long axis of the ellipse of the annular body 30 also rotates at the first rotation speed. Then, the meshing position between the external teeth 32 and the internal teeth 21 also changes in the circumferential direction at the first rotation speed. Also, as described above, the number of internal teeth 21 of the second member 20 and the number of external teeth 32 of the annular body 30 are slightly different. Due to this difference in the number of teeth, the meshing position between the external teeth 32 and the internal teeth 21 slightly changes in the circumferential direction for each rotation of the cam 41 . As a result, the second member 20 rotates about the central axis 9 with respect to the annular body 30 at a second rotation speed lower than the first rotation speed.

<3. Torque sensor>
The power transmission device 1 has a torque sensor 50 . The torque sensor 50 is a sensor for detecting torque applied to the base portion 33 of the annular body 30 described above. As shown in FIG. 2 , the torque sensor 50 has a sensor substrate 51 . The sensor substrate 51 is fixed to the surface of the base portion 33 . FIG. 6 is a partial vertical cross-sectional view of the annular body 30 in the vicinity of the sensor substrate 51. FIG. FIG. 7 is a plan view of the sensor substrate 51. FIG. As shown in FIGS. 6 and 7, the sensor substrate 51 has an insulating layer 511 and resistance lines 512 .

The insulating layer 511 is flexibly deformable. The insulating layer 511 extends in a direction crossing the central axis 9 . Moreover, the insulating layer 511 has an annular shape centered on the central axis 9 . The insulating layer 511 is made of an insulating resin or an inorganic insulating material. The insulating layer 511 is arranged on the surface of the base portion 33 .

A resistance line 512 is formed on the surface of the insulating layer 511 . A metal that is a conductor is used as the material of the resistance wire 512 . A copper alloy, a chromium alloy, or copper, for example, is used as the material of the resistance wire 512 . The resistance wire 512 has a first resistance wire portion W1 and a second resistance wire portion W2. The first resistance wire portion W1 and the second resistance wire portion W2 are strain gauges. That is, the resistance values of the first resistance wire portion W<b>1 and the second resistance wire portion W<b>2 change according to the strain of the base portion 33 .

The first resistance wire portion W1 has an inner first resistance wire portion W11 and an outer first resistance wire portion W12. The outer first resistance wire portion W12 is arranged radially outward of the inner first resistance wire portion W11.

The inner first resistance line portion W11 has two first regions Ra and Rb. The two first regions Ra and Rb are spaced apart in the circumferential direction. The two first regions Ra and Rb are each provided in a semi-arc shape within a range of approximately 180° around the central axis 9 . The two first regions Ra and Rb are arranged concentrically and line-symmetrically. Also, the radial distance from the central axis 9 to the first region Ra is substantially the same as the radial distance from the central axis 9 to the first region Rb.

8 is a partial plan view of the sensor substrate 51. FIG. As shown in FIG. 8, the two first regions Ra and Rb each have a plurality of first regions r1. The first portion r1 extends in a direction having both radial and circumferential components. The plurality of first parts r1 are arranged in the circumferential direction in a posture substantially parallel to each other. Of the two first regions Ra and Rb, the first portion r1 of one of the first regions Ra is inclined to one side in the circumferential direction with respect to the radial direction. The first portion r1 of the other first region Rb is inclined toward the other side in the circumferential direction with respect to the radial direction. The inclination angle of the first portion r1 with respect to the radial direction is, for example, 45°. The ends of the first portions r1 that are adjacent in the circumferential direction are alternately connected on the radially inner side or the radially outer side. As a result, the plurality of first parts r1 are connected in series as a whole.

The outer first resistance line portion W12 has two first regions Rc and Rd. The two first regions Rc and Rd are circumferentially spaced apart. The two first regions Rc and Rd are each provided in a semi-arc shape within a range of approximately 180° around the central axis 9 . The two first regions Rc and Rd are arranged concentrically and line-symmetrically. Also, the radial distance from the central axis 9 to the first region Rc is substantially the same as the radial distance from the central axis 9 to the first region Rd.

As shown in FIG. 8, each of the two first regions Rc and Rd has a plurality of first regions r1. The first portion r1 extends in a direction having both radial and circumferential components. The plurality of first parts r1 are arranged in the circumferential direction in a posture substantially parallel to each other. Of the two first regions Rc and Rd, the first portion r1 of one of the first regions Rc is inclined to the other side in the circumferential direction with respect to the radial direction. The first portion r1 of the other first region Rd is inclined to one side in the circumferential direction with respect to the radial direction. The inclination angle of the first portion r1 with respect to the radial direction is, for example, 45°. The ends of the first portions r1 that are adjacent in the circumferential direction are alternately connected on the radially inner side or the radially outer side. As a result, the plurality of first parts r1 are connected in series as a whole.

The second resistance wire portion W2 has an inner second resistance wire portion W21 and an outer second resistance wire portion W22. The outer second resistance wire portion W22 is arranged radially outward of the inner second resistance wire portion W21.

The inner second resistance wire portion W21 has two second regions Re and Rf. The two second regions Re and Rf are spaced apart in the circumferential direction. The two second regions Re and Rf are each provided in a semicircular arc within a range of approximately 180° around the central axis 9 . The two second regions Re and Rf are arranged concentrically and line-symmetrically. Also, the radial distance from the central axis 9 to the second region Re is substantially the same as the radial distance from the central axis 9 to the second region Rf.

As shown in FIG. 8, the two second regions Re and Rf each have a plurality of second regions r2. The second portion r2 extends in a direction having both radial and circumferential components. The plurality of second parts r2 are arranged in the circumferential direction in a posture substantially parallel to each other. Of the two second regions Re and Rf, the second portion r2 of one of the second regions Re is inclined to one side in the circumferential direction with respect to the radial direction. A second portion r2 of the other second region Rf is inclined toward the other side in the circumferential direction with respect to the radial direction. The inclination angle of the second portion r2 with respect to the radial direction is, for example, 45°. The ends of the second portions r2 adjacent in the circumferential direction are alternately connected on the radially inner side or the radially outer side. As a result, the plurality of second parts r2 are connected in series as a whole.

The outer second resistance line portion W22 has two second regions Rg and Rh. The two second regions Rg and Rh are spaced apart in the circumferential direction. The two second regions Rg and Rh are each provided in a semicircular arc within a range of approximately 180° around the central axis 9 . The two second regions Rg and Rh are arranged concentrically and line-symmetrically. Also, the radial distance from the central axis 9 to the second region Rg is substantially the same as the radial distance from the central axis 9 to the second region Rh.

As shown in FIG. 6, the two second regions Rg and Rh each have a plurality of second regions r2. The second portion r2 extends in a direction having both radial and circumferential components. The plurality of second parts r2 are arranged in the circumferential direction in a posture substantially parallel to each other. Of the two second regions Rg and Rh, the second portion r2 of one of the second regions Rg is inclined to the other side in the circumferential direction with respect to the radial direction. The second portion r2 of the other second region Rh is inclined to one side in the circumferential direction with respect to the radial direction. The inclination angle of the second portion r2 with respect to the radial direction is, for example, 45°. The ends of the second portions r2 adjacent in the circumferential direction are alternately connected on the radially inner side or the radially outer side. As a result, the plurality of second parts r2 are connected in series as a whole.

FIG. 9 is a circuit diagram of a first bridge circuit C1 including four first regions Ra, Rb, Rc, and Rd of the first resistance line portion W1. As shown in FIG. 9, the four first regions Ra, Rb, Rc, and Rd are connected together to form a first bridge circuit C1.

The first region Ra and the first region Rb are connected in series in this order. The first region Rc and the first region Rd are connected in series in this order. A row of the two first regions Ra and Rb and a row of the two first regions Rc and Rd are connected in parallel between the positive and negative poles of the power supply voltage. A midpoint M11 between the two first regions Ra and Rb and a midpoint M12 between the two first regions Rc and Rd are connected to the first voltmeter V1.

The resistance value of each first portion r1 of the four first regions Ra, Rb, Rc, and Rd changes according to the torque applied to the base portion 33. As shown in FIG. For example, when a torque is applied to the base portion 33 toward one side in the circumferential direction about the central axis 9, the resistance value of each first portion r1 of the two first regions Ra and Rd decreases, The resistance value of each first portion r1 of the two first regions Rb and Rc increases. On the other hand, when a torque toward the other side in the circumferential direction is applied to the base portion 33 around the central axis 9, the resistance value of each first portion r1 of the two first regions Ra and Rd increases, The resistance value of each first portion r1 of the two first regions Rb and Rc decreases. In this way, the two first regions Ra and Rd and the other two first regions Rb and Rc show resistance value changes in opposite directions to torque.

Then, when the resistance values of the four first regions Ra, Rb, Rc, and Rd change, the distance between the midpoint M11 between the two first regions Ra and Rb and the midpoint M12 between the two first regions Rc and Rd Since the potential difference between them changes, the measured value of the first voltmeter V1 also changes. Therefore, the direction and magnitude of the torque applied to the base portion 33 can be detected based on the measured value of the first voltmeter V1.

FIG. 10 is a circuit diagram of a second bridge circuit C2 including four second regions Re, Rf, Rg, and Rh of the second resistance line portion W2. As shown in FIG. 10, the four second regions Re, Rf, Rg, and Rh are interconnected to form a second bridge circuit C2.

The second region Re and the second region Rf are connected in series in this order. The second region Rg and the second region Rh are connected in series in this order. A row of two second regions Re and Rf and a row of two second regions Rg and Rh are connected in parallel between the positive and negative poles of the power supply voltage. A midpoint M21 between the two second regions Re and Rf and a midpoint M22 between the two second regions Rg and Rh are connected to the second voltmeter V2.

The resistance value of each second portion r2 of the four second regions Re, Rf, Rg, and Rh changes according to the torque applied to the base portion 33. As shown in FIG. For example, when a torque toward one side in the circumferential direction is applied to the base portion 33 about the central axis 9, the resistance value of each of the second portions r2 of the two second regions Re and Rh decreases, The resistance value of each second portion r2 of the two second regions Rf and Rg increases. On the other hand, when a torque toward the other side in the circumferential direction is applied to the base portion 33 about the central axis 9, the resistance value of each second portion r2 of the two second regions Re and Rh increases, The resistance value of each second portion r2 of the two second regions Rf and Rg is lowered. In this way, the two second regions Re and Rh and the other two second regions Rf and Rg show resistance value changes in opposite directions to torque.

Then, when the resistance values of the four second regions Re, Rf, Rg, and Rh change, the distance between the midpoint M21 between the two second regions Re and Rf and the midpoint M22 between the two second regions Rg and Rh Since the potential difference between them changes, the measured value of the second voltmeter V2 also changes. Therefore, the direction and magnitude of the torque applied to the base portion 33 can be detected based on the measured value of the second voltmeter V2.

The power transmission device 1 further has a housing 60 and a signal processing board 70 . As shown in FIG. 2 , the housing 60 is located on one axial side of the annular body 30 . The housing 60 covers the annular body 30 from one side in the axial direction. Housing 60 is fixed relative to annular body 30 .

A signal processing board 70 is fixed to the surface of the housing 60 . The signal processing board 70 has an arithmetic unit 71 . The calculation unit 71 is configured by an electric circuit having a microprocessor. The calculation unit 71 is electrically connected to the first resistance wire portion W1 and the second resistance wire portion W2. The calculation unit 71 detects the torque applied to the base unit 33 based on the output signals of the first voltmeter V1 and the second voltmeter V2.

Note that the calculation unit outputs the multi-rotation angle of the first member based on the rotation angle detected by the first detection unit described later and the rotation angle detected by the second detection unit described later. Just do it. For example, the calculation unit may perform discrete calculations using analog signal processing and a microcomputer to detect multiple rotation angles of the first member. On the other hand, the torque sensor may be any element that converts the torque applied to the base portion of the power transmission device into an electric signal using a strain gauge or the like. Therefore, the calculation unit and the torque sensor may be configured independently, or may be configured such that some elements or functions are shared in a certain circuit.

As described above, the torque sensor 50 of this embodiment has two bridge circuits, the first bridge circuit C1 and the second bridge circuit C2. Therefore, even if an abnormality occurs in one of the bridge circuits, torque can be detected by the other bridge circuit.

<4. Regarding the First Detector>
The power transmission device 1 has a first detector D1. The first detector D1 is a sensor that detects the rotation angle of the first member 10 . In this embodiment, the sensor substrate 51 of the torque sensor 50 is mounted with the first detection section D1. The first detection section D1 is configured by a resistance wire arranged on the sensor substrate 51 . The resistance value of the resistance wire changes according to the strain of the annular body 30 . That is, the first detector D1 has a strain gauge.

As shown in FIG. 7, the resistance line forming the first detection unit D1 has eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp. The eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp are spaced apart in the circumferential direction. Each of the eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp is formed by one conductor. Each of the third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp extends in an arc shape along the circumferential direction.

Each of the third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, Rp includes a third portion r3. The third portion r3 extends in the circumferential direction. However, the third portions r3 extending in the circumferential direction may be arranged repeatedly in the radial direction. Also, the third portion r3 may extend in the radial direction. Further, the radially extending third portions r3 may be arranged repeatedly in the circumferential direction.

Of the eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the four third regions Ri, Rk, Rm, and Ro that are not adjacent to each other are connected to form a third bridge circuit C3. to form FIG. 11 is a circuit diagram of the third bridge circuit C3. As shown in FIG. 11, the third region Ri and the third region Rk are connected in series in this order. The third region Ro and the third region Rm are connected in series in this order. Between the + and - poles of the power supply voltage, the two columns of the third regions Ri and Rk and the two columns of the third regions Ro and Rm are connected in parallel. A midpoint M31 between the two third regions Ri and Rk and a midpoint M32 between the two third regions Ro and Rm are connected to the third voltmeter V3.

Of the eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp, the remaining four third regions Rj, Rl, Rn, and Rp are connected together to form a fourth bridge circuit C4. Form. FIG. 12 is a circuit diagram of the fourth bridge circuit C4. As shown in FIG. 12, the third region Rp and the third region Rn are connected in series in this order. The third region Rj and the third region Rl are connected in series in this order. A row of two third regions Rp and Rn and a row of two third regions Rj and Rl are connected in parallel between the positive and negative poles of the power supply voltage. A midpoint M41 between the two third regions Rp and Rn and a midpoint M42 between the two third regions Rj and Rl are connected to the fourth voltmeter V4.

When the power transmission device 1 is driven, the base portion 33 of the annular body 30 has a portion that extends in the circumferential direction (hereinafter referred to as "extending portion") and a portion that contracts in the circumferential direction (hereinafter referred to as "contracting portion"). occurs. Specifically, two elongated portions and two contracted portions occur alternately in the circumferential direction. The elongated portion and the contracted portion alternately occur at intervals of 90° in the circumferential direction around the central axis 9 . Then, the locations where these elongated portions and contracted portions are generated rotate at the above-described first rotational speed.

Each resistance value of the eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp changes according to expansion and contraction of the base portion 33 in the circumferential direction. For example, when the extension portion described above overlaps a certain third region, the resistance value of that third region increases. Further, when the contraction portion described above overlaps with a certain third region, the resistance value of the third region is lowered.

In the example of FIG. 7, when the contraction portion overlaps the third regions Ri, Rm, the expansion portion overlaps the third regions Rk, Ro. Further, when the extended portion overlaps with the third regions Ri, Rm, the contracted portion overlaps with the third regions Rk, Ro. Therefore, in the third bridge circuit C3, the third regions Ri, Rm and the third regions Rk, Ro show resistance value changes in opposite directions.

Further, in the example of FIG. 7, when the contraction portion overlaps the third regions Rp, Rl, the expansion portion overlaps the third regions Rn, Rj. Further, when the elongated portion overlaps the third regions Rp, Rl, the contracted portion overlaps the third regions Rn, Rj. Therefore, in the fourth bridge circuit C4, the third regions Rp, Rl and the third regions Rn, Rj show resistance value changes in opposite directions.

FIG. 13 is a graph showing temporal changes in the measured value v3 of the third voltmeter V3 of the third bridge circuit C3 and the measured value v4 of the fourth voltmeter V4 of the fourth bridge circuit C4. The horizontal axis of the graph in FIG. 13 indicates time. The vertical axis of the graph in FIG. 13 indicates the voltage value. When the power transmission device 1 is driven, as shown in FIG. 13, the third voltmeter V3 and the fourth voltmeter V4 output sinusoidal measured values v3 and v4 that change periodically. The cycle T of the measured values v3 and v4 corresponds to 1/2 times (180°) the rotation cycle of the first member 10 described above. Further, whether the phase of the measured value v4 of the fourth voltmeter V4 is ahead of the phase of the measured value v3 of the third voltmeter V3 by ⅛ times (45°) the rotation period of the first member 10, Alternatively, the direction of rotation of the first member 10 is specified depending on whether it is delayed by ⅛ times (45°) the rotation period of the first member 10 .

That is, the first detector D1 detects the rotation angle of the first member 10 based on the measured value v3 of the third voltmeter V3 and the measured value v4 of the fourth voltmeter V4. More specifically, the first detector D1 detects the absolute rotation angle of the first member 10 within the predetermined angle range θ1. "Absolute rotation angle" indicates a rotation angle with respect to a fixed system including the base frame 101, and takes a unique value for each rotation angle. In the present embodiment, the angle range θ1 in which the first detector D1 can detect the absolute rotation angle of the first member 10 is θ1=180°.

As described above, when the power transmission device 1 is driven, the annular body 30 undergoes periodic bending deformation. Therefore, the output signal of the first resistance wire portion W1 and the output signal of the second resistance wire portion W2 include a component reflecting the torque to be originally measured and an error component ( ripple error). The ripple error changes with a period of 180° according to the rotation angle of the first member 10 .

The first detection section D1 is electrically connected to the calculation section 71 described above. The first detector D<b>1 outputs a detection signal indicating the rotation angle of the first member 10 to the calculator 71 . The calculation unit 71 calculates the ripple error described above according to the rotation angle output from the first detection unit D1. Then, the calculation unit 71 corrects the output signal of the first resistance wire portion W1 and the output signal of the second resistance wire portion W2 using the calculated ripple error. As a result, the calculation unit 71 can output the torque applied to the annular body 30 with higher accuracy.

In addition, in the present embodiment, the first detection portion D1 is arranged radially outward of the first resistance wire portion W1 and the second resistance wire portion W2. However, the first detection portion D1 may be arranged radially inward of the first resistance wire portion W1 and the second resistance wire portion W2. Further, the first detection portion D1 may be arranged radially outside the first resistance wire portion W1 and radially inside the second resistance wire portion W2.

<5. Regarding the Second Detector>
The power transmission device 1 has a second detector D2. The second detector D2 is a sensor that detects the rotation angle of the second member 20 . As shown in FIG. 4, the second detector D2 has a detected part D21 and a signal generator D22.

The detected portion D<b>21 is arranged on the second member 20 or a member fixed to the second member 20 . The detected portion D21 has a plurality of patterns arranged in an annular shape with the central axis 9 as the center. The pattern is, for example, grooves or protrusions. The signal generator D22 is arranged on the annular body 30 or a member fixed to the annular body 30 . The signal generator D22 detects the absolute rotation angle of the second member 20 by detecting the pattern of the detected portion D21. For example, a mechanical (contact), optical, magnetic, or capacitive detector can be used as the detection method of the signal generator D22.

The second detector D2 detects the absolute rotation angle of the second member 20 within a predetermined angle range. "Absolute rotation angle" indicates a rotation angle with respect to a fixed system including the base frame 101, and takes a unique value for each rotation angle. In this embodiment, the angle range θ2 in which the second detection unit D2 can detect the absolute rotation angle of the second member 20 is θ2=360°.

However, the second detection unit D2 outputs discrete values represented by a predetermined number of bits B, not continuous values. That is, the second detector D2 detects the rotation angle of the second detector D2 with a resolution of 360°/2̂B. In this way, the configuration of the second detection section D2 can be simplified by making the output value of the second detection section D2 a discrete value instead of a continuous value. Therefore, the cost for the second detector D2 can be reduced.

The number of bits B is a value that satisfies 2̂B≧2N, where N is the speed reduction ratio of the power transmission device 1 (rotational speed of the first member 10/rotational speed of the second member 20). When the speed reduction ratio of the power transmission device 1 ranges from 50 to 160, the number of bits B should be 7 bits (0-127) to 9 bits (0-511).

The second detector D2 is electrically connected to the calculator 71 described above. The second detector D<b>2 outputs a detection signal indicating the rotation angle of the second member 20 to the calculator 71 .

Note that even if the detected portion D21 is arranged on the annular body 30 or a member fixed to the annular body 30, and the signal generating portion D22 is arranged on the second member 20 or a member fixed to the second member 20 good.

<6. Multi-rotation angle detection>
As described above, the first detector D1 detects the absolute rotation angle of the first member 10 within a predetermined angle range. However, the first detection unit D1 alone cannot detect the absolute rotation angle of the first member 10 (hereinafter referred to as "multiple rotation angle") in a range wider than the above angle range. For example, when the angular range in which the first detection unit D1 can detect the absolute rotation angle is 180°, the first detection unit D1 detects when the rotation angle of the first member 10 is 90° and when it is 270°. , cannot be detected separately.

Therefore, the calculation unit 71 outputs the multiple rotation angle of the first member 10 based on the rotation angle detected by the first detection unit D1 and the rotation angle detected by the second detection unit D2.

FIG. 14 is a graph showing an example of output values of the first detection section D1 and the second detection section D2. The horizontal axis of FIG. 14 indicates the multiple rotation angles of the first member 10 . FIG. 14 shows the output value A of the first detection section D1 and the output value P of the second detection section D2. When the power transmission device 1 is driven, while the output value P of the second detection unit D2 changes once from 0° to 360°, the output value A of the first detection unit D1 changes from 0° to 180°. Repeat multiple times. By combining these two output values A and P, the calculation unit 71 outputs the multiple rotation angle of the first member 10 during one rotation of the second member 20 .

Specifically, A is the output value of the first detection unit D1, P is the output value of the second detection unit D2, B is the number of bits of the output value of the second detection unit D2, and the gear ratio of the power transmission device 1 (the second The calculation unit 71 calculates the multi-rotation angle of the first member 10 based on A, P, B, and N, where N is the rotational speed of the first member 10/the rotational speed of the second member 20 . Thereby, the multiple rotation angle of the first member 10 can be output without depending on the encoder of the motor 103 .

More specifically, the angle range in which the first detection unit D1 can detect the absolute rotation angle of the first member 10 is θ1, the angle range in which the second detection unit D2 can detect the absolute rotation angle of the second member 20 is θ2, Let IN be the multi-rotation angle of the first member 10, FLOOR() be the function for truncating decimal places, and MOD _θ1 () be the function representing the remainder when divided by θ1. 2) and (3) calculate IN.
I=(θ2/2̂B)*P*N (1)
IN=FLOOR(I/θ1)*θ1+A (2)
IN={FLOOR(I/θ1)+1}*θ1+A (3)

However, when A≧MOD _θ1 (I), IN is calculated by the above formulas (1) and (2), and when A<MOD _θ1 (I), IN is calculated by the above formulas (1) and (3). do. Thereby, the multiple rotation angle of the first member 10 can be calculated with high accuracy.

Thus, the rotation angle detection device of the present embodiment includes the first detection unit D1 that detects the rotation angle of the first member 10, the second detection unit D2 that detects the rotation angle of the second member 20, and the first A calculation unit 71 that outputs a multi-rotation angle of the first member 10 based on the rotation angle detected by the detection unit D1 and the rotation angle detected by the second detection unit D2. Accordingly, even if the multiple rotation angle of the first member 10 cannot be detected only by the first detector D1, the multiple rotation angle of the first member 10 can be detected from the rotation angle of the second member 20. FIG. Therefore, for example, the multiple rotation angle of the first member 10 can be output without depending on the encoder of the motor 103 .

As described above, the rotation angle detection method of the present embodiment is a rotation angle detection method capable of detecting multiple rotation angles of the first member 10 . That is, the rotation angle detection method of the present embodiment includes a first step of detecting the rotation angle of the first member 10 and the rotation angle of the second member 20, and the rotation angle and the rotation angle of the first member 10 detected in the first step. and a second step of outputting the multiple rotation angle of the first member 10 based on the rotation angle of the second member 20 . As a result, even if the multiple rotation angle of the first member 10 cannot be detected by the first step alone, the multiple rotation angle of the first member 10 can be detected from the rotation angle of the second member 20 . Therefore, for example, the multiple rotation angle of the first member 10 can be output without depending on the encoder of the motor 103 .

As described above, the first detector D1 can detect the absolute rotation angle of the first member 10 only within the predetermined angle range θ1. However, by using not only the output value A of the first detection unit D1 but also the output value P of the second detection unit D2, it is possible to output the multiple rotation angle of the first member 10 in an angle range larger than the above angle range. .

In the present embodiment, θ1=180°, where θ1 is the angle range in which the first detection unit D1 can detect the absolute rotation angle of the first member 10 . As described above, even when the angle range θ1 in which the first detection unit D1 can detect the absolute rotation angle of the first member 10 is less than 360°, if the detection bit number B of the second detection unit D2 is appropriately set, , the multiple rotation angles of the first member 10 can be output.

Further, as described above, the second detection unit D2 can detect the absolute rotation angle of the second member 20 only within the predetermined angle range θ2. In this embodiment, the second detector D2 can detect the absolute rotation angle of the second member 20 only within a range of 360 degrees. However, in applications of the robot 100, the rotation range of the arm 102 is often 360° or less. Therefore, if the multiple rotation angles of the first member 10 can be detected within the range of one rotation of the second member 20, it is sufficient for practical use.

Also, as described above, the second detection unit D2 outputs a discrete value represented by the predetermined number B of bits. The configuration of the second detection unit D2 can be simplified by setting the output value P of the second detection unit D2 to be a discrete value instead of a continuous value. Therefore, the cost for the second detector D2 can be reduced. Further, since the output value P of the second detection unit D2 is a discrete value, simply multiplying the output value P of the second detection unit D2 by the speed reduction ratio N will accurately determine the multi-rotation angle IN of the first member 10. cannot be calculated to However, as described above, by using both the output value A of the first detection unit D1 and the output value P of the second detection unit D2, the multiple rotation angle IN of the first member 10 can be calculated with high accuracy.

Further, as described above, the first detection unit D1 has a strain gauge arranged on the annular body 30 included in the power transmission device 1 . In this embodiment, the first detection section D1 provided for ripple correction of the torque sensor 50 is used for multiple rotation detection of the first member 10 . In other words, the first detector D1 is used for two purposes: ripple correction and multiple rotation detection of the first member 10 . In this way, the number of angle detection units can be reduced compared to the case where the angle detection unit for ripple correction and the angle detection unit for multiple rotation detection of the first member 10 are provided separately. .

Further, as described above, in the present embodiment, the power transmission device 1 has an angle detection device that detects the multiple rotation angle of the first member 10 . Therefore, the multiple rotation angle of the first member 10 can be detected without depending on external elements of the power transmission device 1 such as the encoder of the motor 103 .

Further, as described above, the power transmission device 1 includes the first detection section D1 that detects the rotation angle of the first member 10 and the second detection section D2 that detects the rotation angle of the second member 20. Therefore, the multiple rotation angle of the first member 10 can be detected using the output values of these two detection units.

Further, as described above, the robot 100 has the power transmission device 1 including the first detection section D1 and the second detection section D2. Therefore, for example, it is possible to provide the robot 100 capable of detecting multiple rotation angles of the first member 10 without depending on the encoder of the motor 103 .

<7. Variation>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

<7-1. First modification>
FIG. 15 is a view of the power transmission device 1 according to the first modified example viewed from one side in the axial direction. In the first modification, the first detector D1 has a first sensor and a second sensor.

A 1st sensor has the structure equivalent to the 1st detection part D1 in said embodiment. That is, the first sensor is composed of eight third regions Ri, Rj, Rk, Rl, Rm, Rn, Ro, and Rp arranged on the sensor substrate 51 . The first sensor detects the absolute rotation angle of the first member 10 over an angular range of 180°.

The second sensor has a detected portion D11 and a signal generating portion D12. The detected portion D11 is arranged on the first member 10 or a member fixed to the first member 10 . The detected portion D11 has a pattern formed in an angular range of 180° around the central axis 9 . The pattern is, for example, grooves or protrusions. The signal generator D12 is arranged on the signal processing board 70, for example. The signal generator D12 detects the pattern of the detected portion D11. For example, a mechanical (contact), optical, magnetic, or capacitive detector can be used as the detection method of the signal generator D12. The second sensor outputs a signal with a 360° cycle that switches ON/OFF each time the first member 10 rotates 180°.

In this way, it is possible to specify whether the rotation angle of the first member 10 is in the range of 0 to 180 degrees or in the range of 180 to 360 degrees based on the output signal of the second sensor. can be done. Therefore, the first detector D1 can detect the absolute rotation angle of the first member 10 in the 360° angle range based on the output signal of the first sensor and the output signal of the second sensor. That is, θ1=360°, where θ1 is the angle range in which the first detection unit D1 can detect the absolute rotation angle of the first member 10 . Note that the first detection unit may detect the rotation angle of the first member 10 in the 360° angle range using a single sensor.

<7-2. Second modification>
The output value of the torque sensor 50 may include an error that occurs in one rotation cycle of the second member 20 due to an angle transmission error, eccentricity of the second member 20, or the like. In such a case, the calculation unit 71 calculates the output value of the torque sensor 50 based on the multi-rotation angle IN of the first member 10 calculated based on the output values of the first detection unit D1 and the second detection unit D2. can be corrected. That is, the computing section 71 may correct the output value of the strain gauge based on the multiple rotation angle IN of the first member 10 . Thereby, the torque applied to the annular body 30 can be detected more accurately.

<7-3. Third modification>
FIG. 16 is a diagram showing a portion of the second member 20 and the annular body 30. FIG. As shown in FIG. 16, the second member 20 has multiple internal teeth 21 . That is, the second member 20 has a plurality of teeth arranged in the circumferential direction of the rotating shaft of the second member 20 and extending in the radial direction of the rotating shaft.

Below, the circumferential interval between the tooth tips 21a of the adjacent internal teeth 21 is referred to as "pitch". The plurality of internal teeth 21 are ideally arranged at a constant pitch Pc0 in the circumferential direction. However, due to manufacturing errors in the second member 20, the pitch of some adjacent inner teeth 21 may differ from the ideal pitch Pc0. In the example of FIG. 16, the pitch Pc1 of some adjacent inner teeth 21 is larger than the ideal pitch Pc0. Also, in the example of FIG. 16, the pitch Pc2 of some other adjacent inner teeth 21 is smaller than the ideal pitch Pc0.

Thus, at a position where the pitch of the adjacent internal teeth 21 is different from the ideal pitch Pc0, a deviation occurs in the engagement between the internal teeth 21 and the external teeth 32, causing the annular body 30 and the second member to move about the central axis 9. A deviation occurs in the rotation angle relative to 20 . In other words, a deviation occurs in the relative rotation angle between the first member 10 and the second member 20 around the central axis 9 . Then, as the rotation angle of the first member 10 changes, a deviation occurs between the rotation angle of the second member 20 and the actual rotation angle of the second member 20 . As a result, the arm 102 of the robot 100 may also be misaligned.

Therefore, the calculation unit 71 may store in advance the positional error of each internal tooth 21 in the circumferential direction. Then, the calculation unit 71 may output the absolute rotation angle of each internal tooth 21 in the circumferential direction based on the multi-rotation angle of the first member 10 . That is, the rotation angle detection device may store the angle in the circumferential direction of the tooth. As a result, the rotation angle detection device can output the angle in the circumferential direction of the tooth, or the angle can be read by other parts. In this way, by outputting the rotation angle for each internal tooth 21 based on the pre-stored positional error of each internal tooth 21 in the circumferential direction, the manufacturing error of each internal tooth 21 can be taken into consideration. , the second member 20 can be adjusted to a rotation angle around the central axis 9 that should be accompanied by the rotation of the first member 10 . Therefore, more accurate control can be performed based on the output signal of the rotation angle detection device.

Further, the calculation unit 71 may output the circumferential pitch of the adjacent internal teeth 21 and the absolute rotational angle of the internal teeth 21 in the circumferential direction in association with each other. That is, the rotation angle detection device may store the pitch between the tooth and the tooth adjacent in the circumferential direction and the angle of the tooth in the circumferential direction. Thereby, the rotation angle detection device can output the pitch of teeth adjacent in the circumferential direction and the angle of the tooth in the circumferential direction, or the angle can be read out by other parts. By outputting the pitch of the adjacent internal teeth 21 and the rotation angle of the internal teeth 21 in association with each other in this way, the rotation angle of each internal tooth 21 can be adjusted in consideration of the pitch error. In other words, the second member 20 can be adjusted to the rotation angle around the central axis 9, which should be accompanied by the rotation of the first member 10, taking into consideration the manufacturing error of each pitch. Therefore, more accurate control can be performed based on the output signal of the rotation angle detection device.

Instead of the computing unit, a rotation angle detection device may store the rotation angles of adjacent internal teeth in the circumferential direction. In other words, any portion of the power transmission device may store the rotational angle of the internal teeth in the circumferential direction. Further, the object to be stored by any member of the calculation unit, the rotation angle detection device, or the power transmission device is the rotation angle in the circumferential direction of the external teeth or the pitch in the circumferential direction of the external teeth adjacent in the circumferential direction. It may be the rotational angle in the circumferential direction of both internal and external teeth, or the pitch in the circumferential direction of both internal and external teeth that are circumferentially adjacent.

<7-4. Fourth modification>
In the above embodiment, the power transmission device 1 was provided with the computing section 71 . However, the calculation unit 71 may be provided outside the power transmission device 1 . For example, the robot 100 may include the power transmission device 1 and the computing section 71 . In this case, the calculation unit 71 of the robot 100 can detect the multiple rotation angle of the first member 10 based on the output values of the first detection unit D1 and the second detection unit D2 provided in the power transmission device 1 .

<7-5. Other Modifications>
In the power transmission device 1 of the above embodiment, the annular body 30 is fixed to the base frame 101, and the internal gear, which is the second member 20, rotates at the second rotational speed after deceleration. Therefore, the second detector D2 detects the rotation angle of the internal gear. However, the internal gear may be fixed to the base frame 101 and the annular body 30 may rotate at the second rotational speed after deceleration. In this case, since the annular body 30 is the second member, the second detector D2 may detect the rotation angle of the annular body 30 .

Further, the annular body 30 of the above-described embodiment is a so-called “hat-shaped” flexible external gear in which the base portion 33 spreads radially outward from the body portion 31 . However, the annular body 30 may be a so-called “cup-shaped” flexible external gear in which the base portion 33 extends radially inward from the body portion 31 .

Further, in the above embodiment, the power transmission device 1 mounted on the robot 100 has been described. However, the power transmission device 1 having a similar structure may be mounted on other devices such as an assist suit and an automatic guided vehicle.

In addition, detailed configurations of the rotation angle detection device, the power transmission device, and the robot may be changed as appropriate without departing from the scope of the present invention. In addition, the elements appearing in the above embodiments and modifications may be appropriately combined within a range that does not cause contradiction.

<8. Summary>
The present technology can take the following configurations.

(1) Rotation of a power transmission device having a first member rotating at a first rotation speed and a second member rotating at a second rotation speed lower than the first rotation speed as the first member rotates An angle detection device comprising: a first detection section for detecting the rotation angle of the first member; a second detection section for detecting the rotation angle of the second member; and the rotation angle detected by the first detection section. and a calculation unit that outputs the multiple rotation angle of the first member based on the rotation angle detected by the second detection unit.

(2) The rotation angle detection device according to (1), wherein the first detection unit detects the absolute rotation angle of the first member within a predetermined angle range.

(3) The rotation angle detection device according to (1) or (2), wherein the second detector detects the absolute rotation angle of the second member within a predetermined angle range.

(4) The rotation angle detection device according to any one of (1) to (3), wherein the second detection unit outputs a discrete value indicated by a predetermined number of bits. .

(5) In the rotation angle detection device according to (4), A is the output value of the first detection unit, P is the output value of the second detection unit, B is the number of bits, and B is the number of bits of the power transmission device. The rotation angle detection device, wherein N is a gear ratio, and the calculation unit calculates the multi-rotation angle of the first member based on A, P, B, and N.

(6) In the rotation angle detection device according to (5), the angle range in which the first detection section can detect the absolute rotation angle of the first member is θ1, and the second detection section detects the second Let θ2 be the angle range in which the absolute rotation angle of the member can be detected, IN be the multi-rotation angle of the first member, FLOOR() be the function for rounding off decimals, and MOD _θ1 () be the function representing the remainder when divided by θ1. ,
I=(θ2/2̂B)*P*N (1)
IN=FLOOR(I/θ1)*θ1+A (2)
IN={FLOOR(I/θ1)+1}*θ1+A (3)
When A≧MOD _θ1 (I), the calculation unit calculates IN by the above formulas (1) and (2), and when A<MOD _θ1 (I), by the above formulas (1) and (3) A rotation angle detection device that calculates IN.

(7) In the rotation angle detection device according to any one of (1) to (6), the angle range in which the first detection unit can detect the absolute rotation angle of the first member is θ1, A rotation angle detection device in which θ1=180°.

(8) In the rotation angle detection device according to any one of (1) to (6), the angle range in which the first detection unit can detect the absolute rotation angle of the first member is θ1, A rotation angle detection device in which θ1=360°.

(9) In the rotation angle detection device according to any one of (1) to (8), the first detection section detects the absolute rotation angle of the first member in an angle range of 180°. A rotation angle detection device, comprising: a first sensor; and a second sensor that outputs a signal with a 360° cycle that switches ON/OFF every 180°.

(10) In the rotation angle detection device according to any one of (1) to (9), the second member is arranged in the circumferential direction of the rotation shaft of the second member, and A rotation angle detection device having a plurality of teeth extending in a radial direction, wherein angles of the teeth in the circumferential direction are stored.

(11) In the rotation angle detection device according to any one of (1) to (9), the second member is arranged in the circumferential direction of the rotation shaft of the second member, and A rotation angle detection device having a plurality of teeth extending in a radial direction, wherein pitches between said teeth and said teeth adjacent in said circumferential direction and angles of said teeth in said circumferential direction are stored.

(12) In the rotation angle detection device according to any one of (1) to (11), the first detection section has a strain gauge arranged on an annular body included in the power transmission device. , rotation angle detection device.

(13) The rotation angle detection device according to (12), wherein the calculation unit corrects the output value of the strain gauge based on the multiple rotation angles of the first member.

(14) A power transmission device comprising the rotation angle detection device according to any one of (1) to (13).

(15) A power transmission device having a first member that rotates at a first rotation speed and a second member that rotates at a second rotation speed lower than the first rotation speed as the first member rotates, A rotation angle detection method for detecting multiple rotation angles of the first member, comprising: a first step of detecting a rotation angle of the first member and a rotation angle of the second member; and a second step of outputting a multi-rotation angle of the first member based on the rotation angle of the first member and the rotation angle of the second member.

(16) A first member rotating at a first rotation speed, a second member rotating at a second rotation speed lower than the first rotation speed as the first member rotates, and rotation of the first member A power transmission device comprising: a first detection section that detects an angle; and a second detection section that detects a rotation angle of the second member.

(17) A robot having the power transmission device according to (16).

(18) Multiple rotation of the first member based on the power transmission device according to (16), the rotation angle detected by the first detection unit, and the rotation angle detected by the second detection unit A robot, comprising: a computing unit that outputs an angle.

INDUSTRIAL APPLICABILITY The present invention can be used for a rotation angle detection device, a power transmission device, a rotation angle detection method, and a robot.

Reference Signs List 1 power transmission device 9 central shaft 10 first member 20 second member 21 internal tooth 30 annular body 31 body portion 32 external tooth 33 base portion 34 thick portion 40 wave generator 41 cam 42 flexible bearing 50 torque sensor 51 sensor Board 60 Housing 70 Signal Processing Board 71 Calculation Section 100 Robot 101 Base Frame 102 Arm 103 Motor 511 Insulation Layer 512 Resistance Wire C1 First Bridge Circuit C2 Second Bridge Circuit C3 Third Bridge Circuit C4 Fourth Bridge Circuit D1 First Detector D11 part to be detected D12 signal generation part D2 second detection part D21 part to be detected D22 signal generation part W1 first resistance wire part W2 second resistance wire part

Claims (18)

A rotation angle detection device for a power transmission device having a first member rotating at a first rotation speed and a second member rotating at a second rotation speed lower than the first rotation speed as the first member rotates and
a first detection unit that detects the rotation angle of the first member;
a second detection unit that detects the rotation angle of the second member;
a calculation unit that outputs a multi-rotation angle of the first member based on the rotation angle detected by the first detection unit and the rotation angle detected by the second detection unit;
with
The second detection unit outputs a discrete value indicated by a predetermined number of bits,
The output value of the first detection unit is A,
P is the output value of the second detection unit;
the number of bits is B;
N is the gear ratio of the power transmission device;
As
The rotation angle detection device, wherein the calculation unit calculates a multi-rotation angle of the first member based on A, P, B, and N. The rotation angle detection device according to claim 1,
The rotation angle detection device, wherein the first detection unit detects an absolute rotation angle of the first member within a predetermined angle range. The rotation angle detection device according to claim 1,
The rotation angle detection device, wherein the second detection unit detects an absolute rotation angle of the second member within a predetermined angle range. The rotation angle detection device according to claim 1,
The angle range in which the first detection unit can detect the absolute rotation angle of the first member is θ1,
The angle range in which the second detection unit can detect the absolute rotation angle of the second member is θ2,
IN is the multiple rotation angle of the first member;
FLOOR() is a function that truncates after the decimal point,
MODθ1() is the function that indicates the remainder when divided by θ1.
As
I=(θ2/2̂B)*P*N (1)
IN=FLOOR(I/θ1)*θ1+A (2)
IN={FLOOR(I/θ1)+1}*θ1+A (3)
The calculation unit is
When A≧MOD θ1 (I), IN is calculated by the above formulas (1) and (2),
A rotation angle detection device for calculating IN according to the above equations (1) and (3) when A<MOD θ1 (I). The rotation angle detection device according to claim 1,
Assuming that the angle range in which the first detection unit can detect the absolute rotation angle of the first member is θ1,
θ1=180°
A rotation angle detection device. The rotation angle detection device according to claim 1,
Assuming that the angle range in which the first detection unit can detect the absolute rotation angle of the first member is θ1,
θ1=360°
A rotation angle detection device. The rotation angle detection device according to any one of claims 1 to 6,
The first detection unit is
a first sensor that detects the absolute rotation angle of the first member in an angular range of 180°;
a second sensor that outputs a 360° cycle signal that switches ON/OFF every 180°;
A rotation angle detection device. The rotation angle detection device according to any one of claims 1 to 6,
The second member has a plurality of teeth arranged in the circumferential direction of the rotation shaft of the second member and extending in the radial direction of the rotation shaft,
A rotation angle detection device, wherein angles of the teeth in the circumferential direction are stored. The rotation angle detection device according to any one of claims 1 to 6,
The second member has a plurality of teeth arranged in the circumferential direction of the rotation shaft of the second member and extending in the radial direction of the rotation shaft,
A rotation angle detection device, wherein the pitch between the tooth and the tooth adjacent in the circumferential direction and the angle of the tooth in the circumferential direction are stored. The rotation angle detection device according to any one of claims 1 to 6,
The rotation angle detection device, wherein the first detection unit has a strain gauge arranged on an annular body included in the power transmission device. The rotation angle detection device according to claim 10,
The rotation angle detection device, wherein the calculation unit corrects the output value of the strain gauge based on the multiple rotation angles of the first member. The rotation angle detection device according to any one of claims 1 to 6,
The rotation angle detection device stores at least one of a circumferential rotation angle and a circumferential pitch of at least one of the external teeth of the external gear and the internal teeth of the internal gear included in the power transmission device. , rotation angle detection device. A power transmission device comprising the rotation angle detection device according to any one of claims 1 to 6. In a power transmission device having a first member that rotates at a first rotational speed and a second member that rotates at a second rotational speed lower than the first rotational speed as the first member rotates, the first A rotation angle detection method for detecting multiple rotation angles of a member, comprising:
a first step of detecting the rotation angle of the first member and the rotation angle of the second member;
a second step of outputting a multi-rotation angle of the first member based on the rotation angle of the first member and the rotation angle of the second member detected in the first step;
has
In the second step, outputting a discrete value indicated by a predetermined number of bits;
A is the output value of the rotation angle of the first member;
P is the output value of the rotation angle of the second member;
the number of bits is B;
N is the gear ratio of the power transmission device;
As
The rotation angle detection method, wherein, in the second step, the multiple rotation angles of the first member are output based on A, P, B, and N. The rotation angle detection method according to claim 14,
In the first step, a rotation angle detection method, wherein the rotation angle of the first member is detected by a strain gauge arranged on an annular body included in the power transmission device. a first member rotating at a first rotational speed;
a second member that rotates at a second rotation speed lower than the first rotation speed as the first member rotates;
a first detection unit that detects the rotation angle of the first member;
a second detection unit that detects the rotation angle of the second member;
an annulus;
a calculation unit that outputs a multi-rotation angle of the first member based on the rotation angle detected by the first detection unit and the rotation angle detected by the second detection unit;
with
The second detection unit outputs a discrete value indicated by a predetermined number of bits,
The output value of the first detection unit is A,
P is the output value of the second detection unit;
the number of bits is B;
The transmission gear ratio of the power transmission device is N,
As
The power transmission device, wherein the calculation unit calculates a multi-rotation angle of the first member based on A, P, B, and N. A robot comprising the power transmission device according to claim 16 . A power transmission device according to claim 16;
a calculation unit that outputs a multi-rotation angle of the first member based on the rotation angle detected by the first detection unit and the rotation angle detected by the second detection unit;
A robot with

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